It is well known that light-sensitive silver halide color photographic elements, using the subtractive process for color reproduction, comprise silver halide emulsion layers selectively sensitive to blue, green and red light and associated with yellow, magenta and cyan dye-forming couplers which form (upon exposure and reaction with an oxidized primary amine type color developing agent) the complementary color thereof. For example, an acylacetanilide type coupler is used to form a yellow color image; a 5-pyrazolone, pyrazolotriazole, cyanacetophenone or indazolone type coupler is used to form a magenta color image; and a phenol type, such as a phenol or naphthol, coupler is used to form a cyan color image.
Usually, the color photographic light-sensitive elements comprise non-diffusible couplers incorporated independently in each of the light-sensitive layers of the material (incorporated coupler materials). Therefore, a color photographic light-sensitive element usually comprises 1) a blue-sensitive silver halide emulsion layer (or layers) which contains a yellow dye-forming coupler and which is sensitive to blue light (substantially to wavelengths less than about 500 nm); 2) a green-sensitive silver halide emulsion layer (or layers) which contains a magenta dye-forming coupler and which is mainly sensitive to green light (substantially to wavelengths of about 500 to 600 nm); and 3) a red-sensitive silver halide emulsion layer (or layers) which contains a cyan dye-forming coupler and which is mainly sensitive to red light (substantially to wavelengths longer than about 590 nm). The green-sensitive and the red-sensitive silver halide emulsion layers are rendered sensitive to the green and red regions of the spectrum by associating a spectral sensitizing dye therewith, but retain their inherent sensitivity to blue light.
The differently colored sensitive silver halide emulsion layers are coated on a film base, such a cellulose triacetate (CTA) film or a polyethylenenaphthalate (PEN) film, wherein the uppermost layer (or layers) is the blue-sensitive silver halide emulsion layer (or layers). Thus, to prevent any blue light which passes through the blue sensitive layer from striking the lower sensitive layers, which in addition to being sensitized to particular parts of the spectrum are also sensitive to blue light, and causing a false color rendition, it is common practice to interpose between the source of exposition and the silver halide emulsion layers intended for recording the green and red light, a blue light absorbing layer. Such a layer, usually referred to in the art as yellow filter layer, is commonly interposed between the blue-sensitive silver halide emulsion layer (or layers) and all of the green- and red-sensitive silver halide emulsion layers. The yellow filter layer is useful in absorbing blue light during exposure and must be removed during processing of the photographic element.
As a yellow filter layer it has been a common practice to use a gelatin layer containing dispersed yellow colloidal silver, referred to in the art as Carey Lea silver. The yellow colloidal silver absorbs blue light during exposure and is easily decolored during bleaching and fixing steps of the photographic processing. However, the manufacture of dispersed yellow colloidal silver is expensive, requires time and skill, and the finished dispersion must be maintained in refrigerator stores. Also, the yellow silver can give rise to unwanted photographic fog at the boundaries between the yellow filter layer and the silver halide emulsion layers, so that it may be necessary to coat a barrier layer on each side of the yellow filter layer. Furthermore, the yellow colloidal silver has some adsorption in the green region of the spectrum which results in a diminished effective speed of the element.
It has already been proposed to use yellow dyes as replacement for yellow colloidal silver in yellow filter layers. Yellow dyes as alternatives for yellow colloidal silver are described, for example, in U.S. Pat. Nos. 2,538,008, 2,538,009, and 4,420,555, and GB 695,873 and 760,739. Many of these dyes, although they exhibit satisfactory absorption characteristics, are not completely satisfactory in respect to non-diffusibilty, residual stain after photographic processing, and incubative stain due to reaction with other components of the photographic element.
U.S. Pat. No. 4,923,788 and EP 697,758 describe other yellow dye filters free from drawbacks associated with colloidal silver and other yellow dyes, such as fogging, diffusion, post processing residual stain, and incubative stain.
Therefore, there is still the need in the photographic art to provide satisfactory yellow filter dyes.